Active matrix substrate and a liquid crystal display

ABSTRACT

The present invention provides a liquid crystal display that can reduce occurrence of quality problems and improve adhesive strength between substrates. The present invention is a liquid crystal display including a first substrate, a second substrate, and a seal. The first substrate includes a shift register monolithically formed on an insulating substrate, a plurality of bus lines, a first end, and a display region. The shift register includes a plurality of multistage-connected unit circuits and wiring connected to the plurality of unit circuits, and is arranged in a region between the first end and the display region. At least one of the unit circuits includes a clock terminal, an output terminal, an output transistor, a second transistor, and a bootstrap capacitor. The output transistor and the bootstrap capacitor are arranged in a region between the first end and one of the wiring and the second transistor.

TECHNICAL FIELD

The present invention relates to a liquid crystal display. Moreparticularly, the present invention relates to a liquid crystal displaypreferred for a liquid crystal display including a shift register.

BACKGROUND ART

An active matrix liquid crystal display typically displays an image byselecting pixels arranged in a matrix on a row-by-row basis and writinga voltage in accordance with display data in the selected pixels. Inorder to select pixels on a row-by-row basis, a shift register forsequentially shifting an output signal (scanning signal) based on aclock signal is provided in a gate bus line drive circuit (hereinafterreferred to as a gate driver).

The gate driver may be formed simultaneously with a thin film transistor(TFT) in a pixel by using a manufacturing process for forming the TFT inthe pixel. For example, when a TFT in a pixel is formed using amorphoussilicon, in order to reduce manufacturing costs, preferably the shiftregister included in the gate driver is also formed using amorphoussilicon. In this way, recently, the gate driver has been monolithicallyformed on an array substrate in some cases.

In addition, a one drop filling method (ODF method) has been developedin recent years as a method for filling the interior of a liquid crystalpanel of a liquid crystal display with a liquid crystal material. Theone drop filling method makes it possible to perform a process ofbonding two substrates together and a process of filling the interior ofthe two substrates with the liquid crystal material simultaneously.

Examples of techniques for monolithic formation of the gate driverinclude the following.

A display device is disclosed. In the display device, a display panelincludes a first substrate including a plurality of gate lines and aplurality of data lines, a second substrate facing the first substrate,and a sealing material for bonding the first substrate and the secondsubstrate. A gate driving unit includes a wiring section for receiving aplurality of signals from outside and a circuit section for outputting adriving signal in response to the plurality of signals. The wiringsection includes an aperture for transmitting light incident through aback of the first substrate for hardening the sealing material (forexample, see Patent Literature 1). Patent Literature 1 describes animprovement in bonding force between the first substrate and the secondsubstrate by the sealing material.

A drive unit including a circuit section and a wiring section isdisclosed. The circuit section includes a plurality of cascade-connectedstages and outputs a driving signal based on a plurality of controlsignals. The wiring section includes first and second signal wiring forreceiving a plurality of control signal inputs from outside, firstconnection wiring for connecting the first signal wiring to theplurality of stages, and second connection wiring for connecting thesecond signal wiring to the plurality of stages. The first signalwiring, the first connection wiring, and the second connection wiringare arranged in a layer different from a layer of the second signalwiring (for example, see Patent Literature 2).

A display substrate including gate wiring, a drive circuit section, asignal wiring section, a connection wiring section, and a contactsection is disclosed. The gate wiring is formed in a display region andintersects source wiring. The drive circuit section is formed in aperipheral region surrounding the display region and outputs a gatesignal to the gate wiring. The signal wiring section is formed adjacentto the drive circuit section, extends in an extending direction of thesource wiring, and conveys a driving signal. The connection wiringsection includes an end overlapping the signal wiring section and theother end connected to the drive circuit section electrically. Thecontact section is formed on the signal wiring section and electricallyconnects the one end of the connection wiring section to the signalwiring section (for example, see Patent Literature 3).

A drive circuit including a plurality of drive stages and a dummy stageis disclosed. The plurality of drive stages are cascade-connected toeach other by an output terminal of each stage being connected to acontrol terminal of a previous stage. The plurality of drive stagesoutput switching element driving signals to a plurality of drivingsignal lines each connected to a switching element formed on each pixelarranged in a matrix. In the dummy stage, a dummy output terminal isconnected to each of a control terminal of a last stage among theplurality of drive stages and its own dummy control terminal (forexample, see Patent Literature 4).

A liquid crystal display device is disclosed. In the liquid crystaldisplay device, conventional first auxiliary capacitive trunk wiring isformed to have a narrow width, and new second auxiliary capacitive trunkwiring is further provided and arranged in a position that is theclosest to the outer edge portion of a substrate (for example, seePatent Literature 5). The fifth embodiment and FIG. 13 of PatentLiterature 5 describe a structure in which a slit aperture is providedin a second auxiliary capacitive trunk wiring 440 and wiring 420a for DCvoltage VSS with the largest width among driving signal supply trunkwiring 420.

A TFT is disclosed including a first capacitor formed of a firstcapacitive electrode and a second capacitive electrode, a secondcapacitor formed of a third capacitive electrode and a fourth capacitiveelectrode, first lead-out wiring, second lead-out wiring connected to agate electrode, third lead-out wiring, fourth lead-out wiring, a firstwire, and a second wire (for example, see Patent Literature 6).

A shift register including multistage-connected unit circuits isdisclosed. Each of the unit circuits is provided between a clockterminal and an output terminal, and includes an output transistor forswitching whether to pass a clock signal depending on gate potential,and one or more control transistors with one conducting terminalconnected to a gate of the output terminal. The unit circuit isconfigured so that the gate potential of the output transistor is higherthan high-level potential of the clock signal in a period in which theoutput transistor is turned on and the clock signal is high-level. Thecontrol transistors include a transistor with a channel length longerthan a channel length of the output transistor (for example, see PatentLiterature 7).

A shift register including a plurality of cascade-connected shiftregister stages on a substrate is disclosed. Each of the shift registerstages includes a first transistor including a capacitive electrodefacing at least one of two sources/drain electrodes on an opposite sideof a gate electrode in a film thickness direction. Either one of thecapacitive electrode and one of the source/drain electrodes facing thecapacitive electrode is electrically connected to a control electrode ofan output transistor of the shift register stage (for example, seePatent Literature 8).

Examples of techniques for one drop filling method include thefollowing.

A liquid crystal display panel is disclosed. The liquid crystal displaypanel includes a TFT substrate, a color filter (CF) substrate arrangedto face the TFT substrate, a sealing material sandwiched between the TFTsubstrate and the CF substrate and formed in a peripheral portion of thetwo substrates, and a liquid crystal layer arranged between the TFTsubstrate and the CF substrate. The CF substrate has a light shieldinglayer in the peripheral portion in which the sealing material isprovided. The light shielding layer has a gap in a region overlappingwiring of the TFT substrate (for example, see Patent Literature 9).

A liquid crystal display panel is disclosed. The liquid crystal displaypanel includes an active matrix substrate and an opposed substratearranged opposite to each other, and a liquid crystal layer providedbetween the two substrates, wherein a display region and a non-displayregion in the periphery thereof are defined. In the non-display region,a frame-shaped seal portion including a light-hardening material isprovided between both substrates and has a linear portion with a narrowwidth and a wide portion wider than the linear portion, patternformation of light shielding display wiring is performed on the activematrix substrate, a black matrix formed along an inner periphery end ofthe seal portion and having a cutout at a position corresponding to thewide portion is provided on the opposed substrate (for example, seePatent Literature 10).

A method of manufacturing a liquid crystal optical element is disclosed.The method includes a seal formation process of forming aclosed-circular ultraviolet-hardening seal on a first transparentsubstrate, a liquid crystal dropping process of dropping a liquidcrystal in a region surrounded by the seal, and a main seal hardeningprocess of performing main hardening of the seal after bonding a secondtransparent substrate to the first transparent substrate via the sealwith a predetermined gap. A provisional seal hardening process isperformed between the seal formation process and the liquid crystaldropping process in which a seal inner region is irradiated with theultraviolet light through a mask having a light shielding portion toperform provisional hardening of a partial region of the seal (forexample, see Patent Literature 11).

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2006-39524 A-   Patent Literature 2: JP 2006-79041 A-   Patent Literature 3: JP 2008-26865 A-   Patent Literature 4: JP 2005-522734 T-   Patent Literature 5: WO 2011/067963-   Patent Literature 6: WO 2009/150862-   Patent Literature 7: WO 2010/137197-   Patent Literature 8: WO 2011/135873-   Patent Literature 9: WO 2006/098475-   Patent Literature 10: JP 2007-65037 A-   Patent Literature 11: JP 2009-210965 A

SUMMARY OF INVENTION Technical Problem

With reference to FIG. 19, a liquid crystal display according toComparative Embodiment 1 will be described. The liquid crystal displayaccording to Comparative Embodiment 1 includes an array substrate, anopposed substrate, a seal for bonding both substrates together, and ashift register monolithically formed on the array substrate. The shiftregister includes an output transistor Tr11 connected to a gate busline, a bootstrap capacitor CB11 connected to the output transistorTr11, transistors Tr12 to Tr14, and a wiring group 178 including wirings174 to 176.

The liquid crystal display according to Comparative Embodiment 1 isproduced by a one drop filling method. The seal includes a hardenedmaterial of a light-hardening (for example, ultraviolet-hardening) andthermo-hardening sealing material. The sealing material is hardened tosome extent by light irradiation (provisional hardening), and is fullyhardened by subsequent heat treatment (main hardening). The arraysubstrate includes a strip region (hereinafter referred to as aseal-coating region) 163 sandwiched between thick dashed lines, and theseal is formed in a strip on the seal-coating region 163. One end of theseal-coating region 163 is set between the wiring group 178 and an end110 a of the array substrate, and the other end is set between thebootstrap capacitor CB11 and a region 177 in which the transistors Tr12to Tr14 are arranged.

Here, it is desired that the seal is formed with a width as thin aspossible from the following reasons.

The first reason is that and area of the output transistor Tr11 and thebootstrap capacitor CB11 increases resulting from higher resolution of ascreen and/or a larger screen. As a result, a width of a region 164 inwhich the bootstrap capacitor CB11 and the output transistor Tr11 arearranged tends to become wider. Since the higher resolution and/or thelarger screen involve a higher capability to apply predetermined voltageto a gate of a pixel transistor in a display region, that is, a higherapplication capability, the area of the output transistor Tr11 and thebootstrap capacitor CB11 increases.

The second reason is that a width of a picture-frame region in which agate driver, a source driver, and the like are arranged tends to benarrower as part of pursuit of mobility of an electronic apparatus usinga liquid crystal display. As a result, the width of the seal-coatingregion 163 tends to be narrower.

However, a narrower seal width leads to a smaller adhesion area betweenthe array substrate and the seal, and a smaller adhesion area betweenthe opposed substrate and the seal. Accordingly, peel strength of apanel against physical force applied to the liquid crystal display fromoutside becomes weaker. As a result, quality problems may occur, such asliquid crystal leakage.

If the sealing material is also coated on the output transistor Tr11 andthe bootstrap capacitor CB11, light irradiation of the sealing materialon the output transistor Tr11 and the bootstrap capacitor CB11 may beinsufficient, and provisional hardening of the sealing material may notbe fully performed. This is because the output transistor Tr11 and thebootstrap capacitor CB11 contain a light shielding electrode andfunction as light shielding members, and these members shield light. Inthis case, when a portion of the sealing material that has not undergoneprovisional hardening comes into contact with a liquid crystal material,a sealing material component may dissolve in the liquid crystalmaterial, resulting in occurrence of quality problems, such as displayfailure. Therefore, in Comparative Embodiment 1, it is necessary to setthe seal-coating region 163 in a region other than the output transistorTr11 and the bootstrap capacitor CB11.

The technique described in Patent Literature 11 needs a mask having alight shielding portion in the provisional seal hardening processbetween the seal formation process and the liquid crystal droppingprocess, leading to higher unit prices of the liquid crystal displayitself. In addition, the provisional seal hardening process needs to beperformed before bonding first and second transparent substratestogether, leading to longer time from the provisional hardening processuntil bonding of the both substrates together. Accordingly, there is apossibility of foreign particles, such as dust, mixing in a liquidcrystal layer, causing display quality problems, such as a displaybright defect.

In view of the above state of the art, it is an object of the presentinvention to provide a liquid crystal display that can reduce occurrenceof quality problems, and can improve adhesive strength betweensubstrates.

Solution to Problem

The present inventor made various investigations concerning a liquidcrystal display that can reduce occurrence of quality problems and canimprove adhesive strength between substrates, consequently has notedlayout of elements and wiring contained in a shift register. Then, thepresent inventor found that, in the shift register arranged between afirst end of an array substrate and a display region, by arranging anoutput transistor and a bootstrap capacitor in a region between thefirst end and members other than the output transistor and the bootstrapcapacitor (in more detail, wiring or transistors other than the outputtransistor (second transistor)), it is possible to arrange the wiringand/or the second transistor on a display region side of the outputtransistor and the bootstrap capacitor. In addition, the presentinventor found that it is possible to perform provisional hardening andmain hardening of a sealing material in the region in which the wiringand/or the second transistor are arranged, whereas it is possible toperform main hardening of the sealing material in a region in which theoutput transistor and/or the bootstrap capacitor are arranged.Consequently, the present inventor found that it is possible to controla sealing material component dissolving in a liquid crystal layer, toset a coating region of the sealing material wider, and to controloccurrence of liquid crystal leakage, and perceived that the aboveproblems can be clearly solved. These findings have now led tocompletion of the present invention.

An aspect of the present invention is a liquid crystal display(hereinafter referred to as “display according to the presentinvention”) including a first substrate, a second substrate facing thefirst substrate, and a seal provided in a region between the firstsubstrate and the second substrate, wherein the first substrate includesan insulating substrate, a shift register monolithically formed on theinsulating substrate, a plurality of bus lines, a first end, and adisplay region. The shift register includes a plurality ofmultistage-connected unit circuits and wiring connected to the pluralityof unit circuits, and is arranged in a region between the first end andthe display region. At least one of the plurality of unit circuitsinclude a clock terminal into which a clock signal is input, an outputterminal connected to a corresponding bus line and outputs an outputsignal, a first transistor (output transistor) with one of a source anda drain being connected to the clock terminal and the other of thesource and the drain being connected to the output terminal, a secondtransistor, and a capacitor (bootstrap capacitor) with a first terminalconnected to a gate of the first transistor and a second terminalconnected to the output terminal. The first transistor and the capacitorare arranged in a region between the first end and one of the wiring andthe second transistor.

The configuration of the display according to the present invention isnot particularly limited by other components as long as the display isformed of these components as essential. Here, the shift register mayinclude the plurality of pieces of wiring, and the at least one unitcircuit may include the plurality of second transistors. In these cases,uses of the plurality of pieces of wiring usually differ from eachother, and uses of the plurality of second transistors usually differfrom each other.

Preferred embodiments in the display according to the present inventionwill be described below. The following preferred embodiments may besuitably combined with each other, and an embodiment that combines twoor more of the following preferred embodiments with each other is alsoone of the preferred embodiments.

(A) Preferably, the first substrate includes a first region in which thewiring and/or the second transistor are arranged, and a second region inwhich the first transistor and/or the capacitor are arranged, the sealincludes a first portion adjacent to the liquid crystal layer and asecond portion adjacent to the first portion, and the first portion isarranged on the first region, and the second portion is arranged on thesecond region.

(B) The wiring and the second transistor may be arranged in a regionbetween the display region and one of the first transistor and thecapacitor.

In the embodiment (B), the wiring may be arranged in a region betweenthe second transistor and the display region.

In the embodiment (B), the second transistor may be arranged in a regionbetween the wiring and the display region.

(C) The first transistor and the capacitor may be arranged in a regionbetween the wiring and the second transistor.

In the embodiment (C), the second transistor may be arranged in a regionbetween the first end and one of the first transistor and the capacitor.

In the embodiment (C), the wiring may be arranged in a region betweenthe first end and one of the first transistor and the capacitor. In thiscase, it is possible to protect the first and second transistors fromstatic electricity that intrudes from outside by the wiring.

(D) One of the wiring and the second transistor may be arranged in aregion between the display region and one of the first transistor andthe capacitor, while the other of the wiring and the second transistormay be arranged in a region between the first transistor and thecapacitor.

(E) Preferably, the seal includes a hardened article of alight-hardening and thermo-hardening material.

(F) Preferably, the second substrate includes a light shielding memberthat faces the shift register.

While the use of the wiring is not particularly limited, the followingembodiment (G) is preferable.

(G) A pulse signal is transmitted through the wiring.

While the use of the bus line is not particularly limited, the followingembodiment (H) is preferable. Each of the plurality of bus lines isconnected in common to one row or one column of pixel circuits.

(H) Preferably, the first substrate includes a plurality of pixelcircuits provided in the display region, each of the plurality of pixelcircuits includes a pixel transistor and a pixel electrode connected tothe pixel transistor, and each of the plurality of bus lines isconnected to the plurality of corresponding pixel transistor gates.

Advantageous Effects of Invention

The present invention can achieve a liquid crystal display capable ofreducing occurrence of quality problems and improving adhesive strengthbetween substrates.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic plan view of a liquid crystal panel included in aliquid crystal display according to Embodiment 1.

FIG. 2 is a schematic cross-sectional view taken along the line A-B ofFIG. 1.

FIG. 3 is a schematic plan view of the liquid crystal panel included inthe liquid crystal display according to Embodiment 1.

FIG. 4 is a block diagram illustrating a configuration of the liquidcrystal display according to Embodiment 1.

FIG. 5 is a block diagram illustrating a configuration of a shiftregister according to Embodiment 1.

FIG. 6 is a circuit diagram of a unit circuit included in the shiftregister according to Embodiment 1.

FIG. 7 illustrates a timing chart of the shift register according toEmbodiment 1.

FIG. 8 illustrates a timing chart of the shift register according toEmbodiment 1.

FIG. 9 is a schematic plan view illustrating a configuration in apicture-frame region of the liquid crystal display according toEmbodiment 1.

FIG. 10 is a schematic plan view illustrating the configuration in thepicture-frame region of the liquid crystal display according toEmbodiment 1.

FIG. 11 is a schematic cross-sectional view taken along the line C-D ofFIG. 9.

FIG. 12 is a schematic cross-sectional view taken along the line E-F ofFIG. 9.

FIG. 13 is a diagram illustrating a manufacturing process of the liquidcrystal display according to Embodiment 1.

FIG. 14 is a schematic plan view illustrating the configuration in thepicture-frame region of the liquid crystal display according toEmbodiment 1.

FIG. 15 is a schematic plan view illustrating the configuration in thepicture-frame region of the liquid crystal display according toEmbodiment 2.

FIG. 16 is a schematic plan view illustrating the configuration in thepicture-frame region of the liquid crystal display according toEmbodiment 3.

FIG. 17 is a schematic plan view illustrating the configuration in thepicture-frame region of the liquid crystal display according toEmbodiment 4.

FIG. 18 is a schematic plan view illustrating the configuration in thepicture-frame region of the liquid crystal display according toEmbodiment 5.

FIG. 19 is a schematic plan view illustrating the configuration in thepicture-frame region of the liquid crystal display according toComparative Embodiment 1.

DESCRIPTION OF EMBODIMENTS

The present invention will be mentioned in more detail referring to thedrawings in the following embodiments, but is not limited to theseembodiments.

Embodiment 1

With reference to FIGS. 1 to 14, a liquid crystal display according toEmbodiment 1 will be described. First, with reference to FIGS. 1 to 3,an entire structure of the liquid crystal display according to thepresent embodiment will be described.

The liquid crystal display according to the present embodiment is anactive matrix drive and transmissive liquid crystal display. The liquidcrystal display according to the present embodiment includes a liquidcrystal panel 1, a backlight (not illustrated) arranged behind theliquid crystal panel 1, a control section (not illustrated) for drivingand controlling the liquid crystal panel 1 and the backlight, and aflexible substrate (not illustrated) for connecting the liquid crystalpanel 1 to the control section.

The liquid crystal panel 1 includes a display section 2 for displayingan image. A plurality of pixels 3 are arranged in a matrix in thedisplay section 2. Each of the pixels 3 may include sub pixels of aplurality of colors (for example, three colors of red, green, and blue).In contrast, the liquid crystal display according to the presentembodiment may be a monochrome liquid crystal display. In this case, itis not necessary to divide each pixel 3 into the plurality of subpixels.

The liquid crystal panel 1 includes an array substrate (active matrixsubstrate) 10 corresponding to the above-described first substrate, anopposed substrate 50 corresponding to the above-described secondsubstrate and facing the array substrate 10, a liquid crystal layer(display medium) 61 and a seal 62 provided between the substrates 10 and50, an alignment film (not illustrated) provided on a surface on aliquid crystal layer 61 side of the array substrate 10, an alignmentfilm (not illustrated) provided on a surface on a liquid crystal layer61 side of the opposed substrate 50, and a source driver 5 mounted onthe array substrate 10. In addition, the liquid crystal panel 1, thearray substrate 10, and the opposed substrate 50 include a region(display region) 7 corresponding to the display section 2, and a region(picture-frame region) 8 around the display region 7. The source driver5 is a drive circuit for source bus lines described later.

The seal 62 is formed in the picture-frame region 8 to surround thedisplay region 7. In addition, the seal 62 bonds the substrates 10 and50 together, and seals the liquid crystal layer 61 between thesubstrates 10 and 50.

The array substrate 10 is provided on a back side of the liquid crystaldisplay, and the opposed substrate 50 is provided on an observer side.The array substrate 10 is irradiated with light from the backlight. Animage displayed on the liquid crystal panel 1 is observed from anopposed substrate 50 side. A polarizing plate (not illustrated) isaffixed on a surface of each of the substrates 10 and 50 on an oppositeside of the liquid crystal layer 61. These polarizing plates are usuallydisposed in a cross-Nicol state with each other. The source driver 5 ismounted by a chip on glass (COG) technique in a region of the arraysubstrate 10 that does not face the opposed substrate 50, that is, in aregion protruded from the opposed substrate 50 (hereinafter referred toas an overhang region).

The array substrate 10 includes gate drivers 6 a and 6 b monolithicallyformed on the right and left of the display region 7, terminals 26, 27,28, 29, and 30 formed in the overhang region, source bus lines (datasignal lines) 12 provided to travel vertically through the displayregion 7, gate bus lines (scanning signal lines) 13 and common bus lines17 provided to travel horizontally through the display region 7,lead-out wiring 18 and 19 each formed in the picture-frame region 8,wiring (hereinafter referred to as common trunk wiring) 16 formed in thepicture-frame region 8 to surround the display region 7, and inputwiring 25 formed in the picture-frame region 8. The gate bus lines 13include the gate bus lines 13 connected to output terminals of the leftgate driver 6 a, and the gate bus lines 13 connected to output terminalsof the right gate driver 6 b. These two types of gate bus lines 13 arearranged alternately. The gate bus lines 13 correspond to the bus linein the above-described embodiment (D). The flexible substrate is mountedin a region (region surrounded by a thick alternate long and two shortdashes line in FIG. 3) in which the terminals 26, 28, and 30 areprovided. Each of the source bus lines 12 is connected to an outputsection of the source driver 5 via the corresponding lead-out wiring 18and the terminal 27. Various signals and supply voltages are input intoan input section of the source driver 5 from the control section via theflexible substrate, the terminal 28, the input wiring 25, and theterminal 29. A common signal is input into the common trunk wiring 16from the control section via the flexible substrate and the terminal 30.Here, the common signal is a signal applied in common to all the pixels.The common bus lines 17 are connected to the common trunk wiring 16 inthe picture-frame region 8. The common signal is applied to the commonbus lines 17 from the common trunk wiring 16.

The gate drivers 6 a and 6 b are supplied with various signals andsupply voltages from the control section via the flexible substrate, theterminal 26, and the lead-out wiring 19. Details will be describedlater. All the gate drivers called gate monolithic, gate driverless,gate driver incorporated in panel, gate in panel, gate-on array, and thelike can be included in the gate drivers 6 a and 6 b. Instead of twogate drivers 6 a and 6 b, only one gate driver that performs a functionsimilar to a function of the two gate drivers 6 a and 6 b may beprovided.

The opposed substrate 50 includes a transparent (translucent) insulatingsubstrate 51, a black matrix (BM) 52 that functions as a light shieldingmember, and a plurality of columnar spacers (not illustrated). The BM 52is formed to shield light in the picture-frame region 8 and a regionfacing bus lines. The BM 52 is formed in a frame shape and covers thegate drivers 6 a and 6 b. In FIG. 2, illustration of the BM 52 isomitted in the display region 7. In the display region 7, color filtersof a plurality of colors may be provided. Each of the color filters isformed to cover a region defined by the BM 52, that is, an aperture ofthe BM 52. In addition, the opposed substrate 50 may have a transparent(light-transmissive) overcoat film that covers all the color filters.The columnar spacers are arranged in a light shielding region on the BM52. In addition, particle-shaped spacers (not illustrated) may be mixedin the seal 62. These spacers are members for maintaining a constantdistance between the array substrate 10 and the opposed substrate 50.The distance (cell gap) between both substrates is set to be about 4.0μm.

Examples of materials of the color filter include an acrylic resinobtained by mixing pigments. Examples of materials of the BM 52 includechromium and an acrylic resin obtained by mixing black pigments.Preferably, the BM 52 is formed of an acrylic resin having a thicknessof about 1.0 μm and obtained by mixing black pigments. The overcoat filmis formed of a transparent insulating material. Specifically, alight-transmissive hardening resin, such as an acrylic resin and anepoxy resin, is used. The overcoat film is preferably formed of anacrylic resin, and has a thickness of preferably about 2.0 μm. Theovercoat film has a function of protecting the color filter physicallyor chemically.

A liquid crystal mode of the liquid crystal display of the presentembodiment is not particularly limited. For a liquid crystal mode usinga vertical electric field such as a twisted nematic (TN) mode and avertical alignment (VA) mode, the opposed substrate 50 has a commonelectrode to which the common signal is applied, the array substrate 10has a common transfer electrode 14 connected to the common trunk wiring16, and both electrodes are connected to each other via a conductingmember. The common electrode is formed of a transparent conductivematerial (light-transmissive conductive material), such as an indium tinoxide (ITO), a tin oxide (SnO₂), and an indium zinc oxide (IZO).Preferably ITO is used. Examples of conducting members include ahardening resin in which conductive microparticles are mixed, silver,and carbon paste. Conductive microparticles may be mixed in a sealingmaterial, and the microparticles may be used as a conductive member.Examples of conductive microparticles include microparticles made ofresin with a metal, such as gold, being coated.

Next, with reference to FIGS. 4 to 8, a circuit configuration andoperation of the liquid crystal display of the present embodiment willbe described.

As illustrated in FIG. 4, the liquid crystal display according to thepresent embodiment includes a pixel array 71, a display control circuit72 provided in the control section, the source driver 5, and the gatedrivers 6 a and 6 b.

The pixel array 71 includes n gate bus lines G1 to Gn corresponding tothe gate bus lines 13, m source bus lines S1 to Sm corresponding to thesource bus lines 12, and (m×n) pixel circuits Pij each formed in thepixel 3. n and m are each an integer greater than or equal to two, i isan integer from one to n inclusive, and j is an integer from one to minclusive. The gate bus lines G1 to Gn are arranged parallel to eachother, whereas the source bus lines S1 to Sm are arranged parallel toeach other to be orthogonal to the gate bus lines G1 to Gn. Each of thepixel circuits Pij is arranged near an intersection of the gate bus lineGi and the source bus line Sj. In this way, (m×n) pixel circuits Pij aretwo-dimensionally arranged with m pieces in a row direction and n piecesin a column direction. The gate bus line Gi is connected in common tothe pixel circuits Pij arranged in the ith row, whereas the source busline Sj is connected in common to the pixel circuits Pij arranged in thejth column. Each of the pixel circuits Pij is provided with a pixel TFT4 as a switching element and a pixel electrode 9. A gate of the TFT 4 isconnected to the gate bus line Gi. Among a drain and source of the TFT4, one is connected to the source bus line Sj, and the other isconnected to the pixel electrode 9.

Control signals, such as a horizontal synchronization signal HSYNC and avertical synchronizing signal VSYNC, and an image signal DAT aresupplied from outside the liquid crystal display of the presentembodiment. Based on these signals, the display control circuit 72outputs clock signals CK1, CK2, and a start pulse SP1 to the gate driver6 a. The display control circuit 72 outputs clock signals CK3, CK4, anda start pulse SP2 to the gate driver 6 b. The display control circuit 72outputs a control signal SC and a digital video signal DV to the sourcedriver 5.

The gate driver 6 a includes a shift register 73 a. The shift register73 a includes a plurality of multistage-connected unit circuits SR1,SR3, . . . , SRn−1. The unit circuits SR1, SR3, . . . , SRn−1 areconnected to the odd-numbered gate bus lines G1, G3, . . . , Gn−1,respectively.

The gate driver 6 b includes a shift register 73 b. The shift register73 b includes a plurality of multistage-connected unit circuits SR2,SR4, . . . , SRn. The unit circuits SR2, SR4, . . . , SRn are connectedto the even-numbered gate bus lines G2, G4, . . . , Gn, respectively.

The shift registers 73 a and 73 b control output signals SROUT1 toSROUTn to high-level (indicating a selected state) sequentiallyone-by-one. The output signals SROUT1 to SROUTn are provided to the gatebus lines G1 to Gn, respectively. This causes the gate bus lines G1 toGn to be sequentially selected one-by-one, and the pixel circuits Pij inone row are collectively selected. That is, the pixel TFTs 4 of thepixel circuits Pij in one row are turned on.

Based on the control signal SC and the digital video signal DV, thesource driver 5 applies voltages according to the digital video signalDV to the source bus lines S1 to Sm. This causes the voltages accordingto the digital video signal DV to be written in the pixel circuits Pijin the selected one row. Thus, the liquid crystal display of the presentembodiment displays an image.

As illustrated in FIG. 5, each of the unit circuits SR1 to SRn includesinput terminals INa, INb, clock terminals CKA, CKB, a power terminalVSS, and an output terminal OUT.

The shift register 73 a is supplied with the start pulse SP1, an endpulse EP1, the two-phase clock signals CK1, CK2, and a low-levelpotential VSS (a symbol identical to a symbol of the power terminal isassigned for convenience). The start pulse SP1 is input into the inputterminal INa of the first-stage unit circuit SR1 in the shift register73 a. The end pulse EP1 is input into the input terminal INb of thefinal-stage unit circuit SRn−1 in the shift register 73 a. The clocksignal CK1 is input into the clock terminals CKA of odd-numbered-stageunit circuits in the shift register 73 a and the clock terminals CKB ofeven-numbered-stage unit circuits in the shift register 73 a. The clocksignal CK2 is input into the clock terminals CKA of even-numbered-stageunit circuits in the shift register 73 a and the clock terminals CKB ofodd-numbered-stage unit circuits in the shift register 73 a. Thelow-level potential VSS is input into the power terminals VSS of all theunit circuits in the shift register 73 a. The output signals SROUT1,SROUT3, . . . , SROUTn−1 are output from the output terminals OUT of theunit circuits SR1, SR3, . . . , SRn−1, respectively. The output signalsSROUT1, SROUT3, . . . , SROUTn−1 are output to the gate bus lines G1,G3, . . . , Gn−1, respectively. In addition, each output signal is inputinto the input terminal INa of the second-back-stage (first-back stagein the shift register 73 a) unit circuit, and into the input terminalINb of the fourth-previous-stage (second-previous stage in the shiftregister 73 a) unit circuit.

The shift register 73 b is supplied with the start pulse SP2, an endpulse EP2, the two-phase clock signals CK3, CK4, and the low-levelpotential VSS. The start pulse SP2 is input into the input terminal INaof the first-stage unit circuit SR2 in the shift register 73 b. The endpulse EP2 is input into the input terminal INb of the final-stage unitcircuit SRn in the shift register 73 b. The clock signal CK3 is inputinto the clock terminals CKA of odd-numbered-stage unit circuits in theshift register 73 b and the clock terminals CKB of even-numbered-stageunit circuits in the shift register 73 b. The clock signal CK4 is inputinto the clock terminals CKA of even-numbered-stage unit circuits in theshift register 73 b and the clock terminals CKB of odd-numbered-stageunit circuits in the shift register 73 b. The low-level potential VSS isinput into the power terminals VSS of all the unit circuits in the shiftregister 73 b. The output signals SROUT2, SROUT4, . . . , SROUTn areoutput from the output terminals OUT of the unit circuits SR2, SR4, . .. , SRn, respectively. The output signals SROUT2, SROUT4, . . . , SROUTnare output to the gate bus lines G2, G4, . . . , Gn, respectively. Inaddition, each output signal is input into the input terminal INa of thesecond-back-stage (first-back stage in the shift register 73 b) unitcircuit, and into the input terminal INb of the fourth-previous-stage(second-previous stage in the shift register 73 b) unit circuit.

Although it is preferable that the low-level potential VSS is negativepotential from a viewpoint of securely turning off an n-channel TFT, thelow-level potential VSS may be positive potential when used for ap-channel TFT as the pixel TFT 4.

As illustrated in FIG. 6, each unit circuit includes n-channel-TFTtransistors Tr1 to Tr4, and a capacitor (hereinafter referred to as abootstrap capacitor) CB1. Hereinafter, the transistor Tr1 is referred toas an output transistor Tr1.

A drain of the output transistor Tr1 is connected to the clock terminalCKA, and a source is connected to the output terminal OUT. A drain andgate of the transistor Tr2 are connected to the input terminal INa, anda source is connected to agate of the output transistor Tr1. Thebootstrap capacitor CB1 is provided between the gate and source of theoutput transistor Tr1. One terminal of the bootstrap capacitor CB1 isconnected to the gate of the output transistor Tr1, and the otherterminal is connected to the output terminal OUT. A drain of thetransistor Tr3 is connected to the output terminal OUT, a gate isconnected to the clock terminal CKB, and a source is connected to thepower terminal VSS. A drain of the transistor Tr4 is connected to thegate of the output transistor Tr1, a gate is connected to the inputterminal INb, and a source is connected to the power terminal VSS.

The output transistor Tr1 is provided between the clock terminal CKA andthe output terminal OUT, and functions as a transistor (transmissiongate) for switching whether to allow a clock signal to pass depending ongate potential. The gate of the output transistor Tr1 is capacitivelycoupled with a conducting terminal (source) on the output terminal OUTside. As a result, as will be described later, in a period when theoutput transistor Tr1 is on and the clock signal CK1 or CK3 that isinput into the clock terminal CKA (hereinafter referred to as a clocksignal CKA) is high-level, the gate potential of the output transistorTr1 becomes higher than the high-level potential of the clock signalCKA. Hereinafter, a node to which the gate of the output transistor Tr1is connected is referred to as netA.

FIGS. 7 and 8 each illustrate a timing chart of the shift registers 73 aand 73 b. FIG. 7 illustrates input and output signals and voltagechanges at the node netA of an odd-numbered-stage unit circuit in eachshift register.

As illustrated in FIG. 7, in the odd-numbered-stage unit circuit in eachshift register, the clock signal CK1 or CK3 is input via the clockterminal CKA, and the clock signal CK2 or CK4 is input via the clockterminal CKB. A period when potential of each of the clock signals CK1to CK4 is high-level is substantially identical to ½ period. The clocksignal CK2 is a signal obtained by delaying the clock signal CK1 by ½period. The clock signal CK3 is a signal obtained by delaying the clocksignal CK1 by ¼ period. The clock signal CK4 is a signal obtained bydelaying the clock signal CK2 by ¼ period.

The start pulses SP1 and SP2 become high-level before a shiftingoperation starts for a period identical to a period of high-levelpotential of the clock signals CK2 and CK4, respectively. The end pulsesEP1 and EP2 (not illustrated in FIGS. 7 and 8) become high-level afterthe shifting operation ends for a period identical to a period ofhigh-level potential of the clock signals CK2 and CK4, respectively.

With reference to FIG. 7, an operation of the odd-numbered-stage unitcircuit in each shift register will be described. First, when a signal(start pulses SP1, SP2, or an output signal of a second-previous-stageunit circuit (previous stage in each shift register), hereinafterreferred to as an input signal INa) input into the input terminal INachanges from low-level to high-level, potential at the node netA alsochanges to high-level via the diode-connected transistor Tr2, and theoutput transistor Tr1 is turned on.

Next, when the input signal INa changes to low-level, the transistor Tr2is turned off, and the node netA enters a floating state, but the outputtransistor Tr1 maintains on-state.

Next, when the clock signal CKA (clock signal CK1 or CK3) changes fromlow-level to high-level, the bootstrap capacitor CB1 is charged, and abootstrap effect raises the potential at the node netA to about twice anamplitude Vck (=(high-level potential VGH)−(low-level potential VGL)) ofthe clock signal CKA. Since the gate potential of the output transistorTr1 is sufficiently high, resistance between the source and drain of theoutput transistor Tr1 becomes smaller, and the clock signal CKA passesthrough the output transistor Tr1 without a voltage drop.

While the clock signal CKA is high-level, the potential at the node netAis about twice Vck, and the output signal SROUT is high-level.

Next, when the clock signal CKA changes to low-level, the potential atthe node netA becomes high-level. At the same time, since the clocksignal CK2 or CK4 input into the clock terminal CKB (hereinafterreferred to as a clock signal CKB) changes to high-level, the transistorTr3 is turned on, and low-level potential VSS is applied to the outputterminal OUT. Consequently, the output signal SROUT becomes low-level.

Next, when a signal (end pulses EP1, EP2, or an output signal of afourth-back-stage unit circuit (second-back stage in each shiftregister), hereinafter referred to as an input signal INb) input intothe input terminal INb changes from low-level to high-level, thetransistor Tr4 is turned on. When the transistor Tr4 is turned on, thelow-level potential VSS is applied to the node netA, the potential atthe node netA changes to low-level, and the output transistor Tr1 isturned off.

Next, when the input signal INb changes to low-level, the transistor Tr4is turned off. At this time, the node netA enters a floating state, butthe output transistor Tr1 maintains off-state. Until the input signalINa becomes high-level next time, ideally, the output transistor Tr1maintains off-state, and the output signal SROUT maintains low-level.

Then, the transistor Tr3 is turned on when the clock signal CKB becomeshigh-level. Accordingly, every time the clock signal CKB becomeshigh-level, the low-level potential VSS is applied to the outputterminal OUT. In this way, the transistor Tr3 has a function torepeatedly set the output terminal OUT to the low-level potential VSSand to stabilize the output signal SROUT.

The even-numbered-stage unit circuit also operates in the same manner asin the odd-numbered-stage unit circuit.

Consequently, as illustrated in FIG. 8, gate pulses are sequentiallyoutput to the gate bus lines G1, G2, G3, . . . .

Next, with reference to FIGS. 9 to 14, a configuration in thepicture-frame region of the liquid crystal display according to thepresent embodiment will be described.

As illustrated in FIG. 9, a wiring group 78 extending in a directionorthogonal to the above-described gate bus lines 13 is provided in eachgate driver. The wiring group 78 includes wiring 74 that is set at thelow-level potential VSS, wiring 75 for transmitting the clock signal CK1or CK3, and wiring 76 for transmitting the clock signal CK2 or CK4. Aslit aperture is formed in each piece of the wiring.

The output transistor Tr1 and the bootstrap capacitor CB1 are arrangedadjacent to each other. The transistors Tr2 to Tr4 are arranged adjacentto each other. A region (hereinafter referred to as a control elementregion) 77 in which the transistors Tr2 to Tr4 are arranged is locatedbetween the wiring group 78 and the output transistor Tr1. The outputtransistor Tr1 and the bootstrap capacitor CB1 are arranged on an end 10a side (on an opposite side of the display region 7) of the controlelement region 77 and the wiring group 78.

As illustrated in FIG. 10, the array substrate 10 includes a stripregion (hereinafter referred to as a seal-coating region) 63 sandwichedbetween thick dashed lines. The seal 62 is formed in a strip on theseal-coating region 63 so that the seal 62 does not protrude from theseal-coating region 63. One end of the seal-coating region 63 is set ina region between the bootstrap capacitor CB1 and the end 10 a of thearray substrate 10, whereas the other end is set in a region between thewiring 74 and the display region 7. The seal-coating region 63 includesa region 65 in which the transistors Tr2 to Tr4 and the wiring 74 to 76(wiring group 78) are arranged, and a region 64 in which the outputtransistor Tr1 and the bootstrap capacitor CB1 are arranged. The region65 corresponds to the above-described first region, and the region 64corresponds to the above-described second region. In this way, in thepresent embodiment, different from Comparative Embodiment 1, the outputtransistor Tr1 and the bootstrap capacitor CB1 are arranged in theseal-coating region 63.

The seal 62 is arranged to cover at least part or all of the outputtransistor Tr1 and a partial region or entire region of the controlelement region 77. As long as the seal 62 does not protrude from theseal-coating region 63, it is not particularly limited whether the seal62 covers regions other than these regions. For example, the seal 62 maybe arranged to cover part or all of the output transistor Tr1, theentire region of the control element region 77, and part or all of thewiring 76. The seal 62 may be arranged to cover part or all of thebootstrap capacitor CB1, all of the output transistor Tr1, the entireregion of the control element region 77, all of the wiring 76, and partor all of the wiring 75. The seal 62 may be arranged to cover part orall of the bootstrap capacitor CB1, all of the output transistor Tr1,the entire region of the control element region 77, all of the wiring76, all of the wiring 75, and part or all of the wiring 74. In this way,the seal 62 includes a first portion that is adjacent to the liquidcrystal layer 61 and a second portion that is adjacent to the firstportion. The first portion is arranged on the region 65, whereas thesecond portion is arranged on the region 64.

Each of the transistors Tr1 to Tr4 is a bottom gate thin filmtransistor, and particularly the output transistor Tr1 is large and hasa comblike source/drain structure. This enables each transistor tosecure a large channel width, for example, on the order of ten μm tohundred mm.

As illustrated in FIG. 11, the array substrate 10 includes a transparent(translucent) insulating substrate 11. The output transistor Tr1includes a gate electrode 41 on the insulating substrate 11, a gateinsulator 42 on the gate electrode 41, an i layer (semiconductor activelayer) 43 on the gate insulator 42, an n+ layer 44 on the i layer 43,and a source electrode 45 and drain electrode 46 that are each providedon the n+ layer 44. The source electrode 45 and the drain electrode 46each include a plurality of comblike portions. The source electrode 45and the drain electrode 46 are arranged face to face so that thecomblike portions mesh each other.

As illustrated in FIG. 12, the bootstrap capacitor CB1 includes a firstelectrode 31 on the insulating substrate 11, the gate insulator 42 thatis provided on the first electrode 31 and shared by the outputtransistor Tr1, and a second electrode 32 on the gate insulator 42.

In order for the array substrate 10 and the opposed substrate 50 to belight-transmissive, as a material for the insulating substrates 11 and51, inorganic substances, such as glass, silica glass, and siliconnitride, organic polymer compounds (resin), such as an acrylic resin,are mainly used. Preferably, silica glass with a thickness of about 0.7mm is used.

The gate electrode 41 and the first electrode 31 are each formed of acommon conductive film containing a material, such as molybdenum (Mo),titanium (Ti), aluminum (Al), copper (Cu), and an alloy of these metals.The gate electrode 41 and the first electrode 31 may be formed of amultilayer film of these conductive films. Preferably, Al is used. Thegate insulator 42 is formed of a transparent (translucent) insulatinglayer containing an inorganic insulating material, such as siliconnitride and silicon oxide. The gate insulator 42 may be formed using amultilayer film of these insulating layers. The i layer (semiconductoractive layer) 43 is formed of amorphous silicon, and the n+ layer 44 isformed of amorphous silicon containing impurities (for example,phosphorus). The source electrode 45, the drain electrode 46, and thesecond electrode 32 are each formed of a common conductive filmcontaining a material, such as Mo, Ti, Al, Cu, and an alloy of thesemetals. The source electrode 45, the drain electrode 46, and the secondelectrode 32 may be each formed of a multilayer film of these conductivefilms.

A transparent (translucent) insulating layer 47 that functions as apassivation film is formed on the source electrode 45, the drainelectrode 46, and the second electrode 32. The insulating layer 47 isformed of an inorganic insulating layer, such as a silicon nitride filmand a silicon oxide film. The insulating layer 47 may be formed using amultilayer film of these inorganic insulating layers. A transparent(translucent) insulating layer 48 that functions as a planarization filmis formed on the insulating layer 47. The insulating layer 48 is formedof an organic insulating layer. Examples of materials of the organicinsulating layer include a photosensitive resin, such as aphotosensitive acrylic resin.

Each of the transistors Tr2 to Tr4 differs from the output transistorTr1 only in a planar structure, and has a cross-sectional structuresimilar to the structure of the output transistor Tr1. In each diagram,a shaded member, and the gate electrode 41 and the first electrode 31are formed of a common conductive film, while a member with dotpatterns, the source electrode 45, the drain electrode 46, and thesecond electrode 32 are formed of a common conductive film. In eachdiagram, a white-coated rectangular region arranged in a region in whichthe shaded member and the member with dot patterns overlap each otherrepresents a contact hole for connecting both members to each other.

The pixel TFT 4 is a bottom gate thin film transistor in the same manneras in the output transistors Tr1 to Tr4, and is formed together with theoutput transistors Tr1 to Tr4 through a common process.

In the display region 7, the above-described pixel electrode 9 is formedon the insulating layer 48. The pixel electrode 9 is electricallyconnected to the drain electrode (not illustrated) of the pixel TFT 4through a contact hole (not illustrated) that passes through theinsulating layers 47 and 48. The pixel electrode 9 is formed of atransparent conductive material (light-transmissive conductivematerial), such as ITO, SnO₂, and IZO.

Next, a method for manufacturing the liquid crystal display of thepresent embodiment will be described. The liquid crystal display of thepresent embodiment can be manufactured by a general method. Moreparticularly, first, a substrate (hereinafter referred to as an arraymother glass) before being divided into a plurality of array substrates10, and a substrate (referred to as a CF mother glass) before beingdivided into a plurality of opposed substrates 50 are each produced by ausual method.

After the array mother glass and the CF mother glass are produced, stepsS11 to S19 are performed as illustrated in FIG. 13.

First, in step S11 (substrate cleaning process), the array mother glassand the CF mother glass are cleaned.

A degassing process may be performed between step S11 and step S12. Inthe degassing process, the array mother glass and the CF mother glassare heated to remove unnecessary substances, such as an organic solventand gas from these mother glasses.

Next, in step S12 (alignment film formation process), an alignment filmis formed on each of the array mother glass and the CF mother glass.Examples of materials for the alignment film include an organic materialsuch as polyimide and an inorganic material such as a silicon oxide.

Next, in step S13 (rubbing process), rubbing treatment is applied toeach alignment film. Step S13 may be omitted depending on an alignmentstate of liquid crystal molecules in the liquid crystal layer 61.Instead of the rubbing treatment, alignment treatment other than therubbing treatment may be applied, for example, optical alignmenttreatment.

Next, in step S14 (seal-coating process), a material (hereinafterreferred to as a sealing material) for a seal before hardening is coatedon one of the array mother glass and the CF mother glass by a methodsuch as a screen printing method and a dispenser writing method. Thesealing material is pasty and is coated in a closed ring. This sealingmaterial is a hardening (for example, ultraviolet-hardening) andthermo-hardening material (hereinafter referred to as light/heatcombined use sealing material), and generally includes an acrylic resinand/or an epoxy resin. Specific examples of light/heat combined usesealing materials include the Photolec S series (made by SEKISUICHEMICAL CO., LTD.) that uses an epoxy acrylic resin as a maincomponent. The sealing material is preferably coated by a dispenserwriting method.

Next, in step S15 (liquid crystal material dropping and bondingprocess), a liquid crystal material is dropped on a mother glass onwhich the sealing material is coated, a mother glass on which thesealing material is not coated, or both of the mother glasses, then bothmother glasses are bonded together. Bonding of both mother glasses isperformed under environments with pressures lower than atmosphericpressures (for example, under vacuum). Both mother glasses are placedunder atmospheric pressures after bonding. The liquid crystal materialis preferably dropped on the CF mother glass.

Next, in step S16 (provisional seal hardening process), the sealingmaterial is irradiated with light from an array mother glass side toharden (provisional hardening) the sealing material to some extent. Atthis time, since the light is shielded by the output transistor Tr1 andthe bootstrap capacitor CB1, the sealing material on the outputtransistor Tr1 and the bootstrap capacitor CB1 is irradiated withinsufficient light, and the sealing material hardly undergoesprovisional hardening. However, since the region 65 in which thetransistors Tr2 to Tr4 and the wiring 74 to 76 are arranged includesmany translucent regions, the sealing material can fully undergoprovisional hardening on the region 65. In addition, a sealing materialportion (portion corresponding to the above-described first portion)that has undergone provisional hardening is arranged closer to thedisplay region 7, and a sealing material portion (portion correspondingto the above-described second portion) that has not undergoneprovisional hardening is arranged closer to the end 10 a of the arraysubstrate 10. This can prevent the sealing material portion that has notundergone provisional hardening from touching the liquid crystal layer,and thus can prevent a sealing material component from dissolving anddiffusing into the liquid crystal layer. The sealing material isirradiated with light from the array substrate 10 side because the BM 52is formed on the opposed substrate 50. Types of light used forirradiation is not limited, and may include, for example, lightincluding ultraviolet light. Preferably, ultraviolet light is used.

Next, in step S17 (main seal hardening process), the bonded motherglasses are heated. The heating further hardens the sealing material(main hardening). All of the sealing material hardens in this process.Accordingly, on the region 64 in which the output transistor Tr1 and thebootstrap capacitor CB1 are arranged, the sealing material hardlyundergoes provisional hardening in step S16, and undergoes mainhardening in step S17. On the other hand, on the region 65 in which thetransistors Tr2 to Tr4 and the wiring 74 to 76 are arranged, the sealingmaterial undergoes provisional hardening in step S16, and undergoes mainhardening in step S17.

In this way, in the present embodiment, the sealing material portion(portion corresponding to the above-described first portion) thatundergoes provisional hardening and main hardening is arranged closer tothe display region 7, while the sealing material portion (portioncorresponding to the above-described second portion) that does notundergo provisional hardening and undergoes main hardening is arrangedcloser to the end 10 a of the array substrate 10.

While the technique described in Patent Literature 11 needs to performprovisional hardening of the sealing material before bonding substratestogether, the present embodiment performs provisional hardening of thesealing material after bonding mother glasses together. This can preventforeign substances, such as dust, from mixing in the liquid crystallayer. Furthermore, the present embodiment does not need a mask forprovisional hardening. This can reduce manufacturing costs.

While conditions for light irradiation and heat treatment in steps S16and S17 can be suitably set in accordance with characteristics of thesealing material, when the Photolec S series is used, for example,ultraviolet irradiation of around 10 J is performed, and heat treatmentat 120° C. is performed for 60 minutes.

Next, in step S18 (breaking process), the bonded mother glasses arebroken along panel breaking lines into a plurality of liquid crystalcells.

Next, in step S19 (inspection process), inspections such as a lightinginspection of the liquid crystal cell are performed to check qualityconditions of the liquid crystal cell.

Subsequently, after the polarizing plate and phase plate (optional) areaffixed on each of both surfaces of the liquid crystal cell, the sourcedriver 5 is mounted and the liquid crystal panel 1 is completed. Then,the flexible substrate is connected to the liquid crystal panel 1, thecontrol section and the backlight unit are attached, and thesecomponents are accommodated in an enclosure, thereby completing theliquid crystal display of Embodiment 1.

In the present embodiment, the output transistor Tr1 and the bootstrapcapacitor CB1 are arranged in a region between the end 10 a of the arraysubstrate 10 and the control element region 77. Accordingly, each of thetransistors in the control element region 77 and the wiring group 78 canbe arranged on a display region 7 side of the output transistor Tr1 andthe bootstrap capacitor CB1. In addition, it is possible to performprovisional hardening and main hardening of the sealing material on theregion 65 in which the transistors Tr2 to Tr4 and the wiring 74 to 76are arranged. On the other hand, it is possible to perform mainhardening of the sealing material on the region 64 in which the outputtransistor Tr1 and the bootstrap capacitor CB1 are arranged.Consequently, it is possible to control the sealing material componentfrom dissolving in the liquid crystal layer by the time of completion ofthe main seal hardening process. In addition, it is possible to definethe seal-coating region 63 to be wider. Furthermore, it is possible tocontrol occurrence of liquid crystal leakage. Therefore, it is possibleto reduce occurrence of quality problems and to improve adhesivestrength between substrates.

Although a size of each element and a thickness of each piece of wiringare not particularly limited and can be suitably configured, forexample, values illustrated in FIG. 14 can be applied. A thickness ofthe wiring 74 and a thickness of the wiring 75 are substantiallyidentical to a thickness of the wiring 76. Spacing of the wiring 74 andthe wiring 75 can be set to 30 μm. A pitch of the output transistor issubstantially equal to a pitch of the unit circuit or the gate bus line.Furthermore, a width of wiring that connects between elements or betweenan element and wiring can be set to, for example, 10 μm.

In the case illustrated in FIG. 14, a proportion of an area in whichlight is shielded in a region A including the transistors Tr2 to Tr4,the wiring 76, and the wiring 75 is roughly estimated to be about 25%(=(105×70+50×70+30×60+20×20×6×six contacts+30×200×four linear parts ofwiring)/(800×200)=39050/160000). On the other hand, a proportion of anarea in which light is shielded in a region B including the outputtransistor Tr1 and the bootstrap capacitor CB1 is roughly estimated tobe about 80% (=(80×190+200×160)/(300×200)=47200/600). In this way, theproportion of the area in which light is shielded in the region A ispreferably 50% or smaller, and the proportion of the area in which lightis shielded in the region B is preferably larger than 50%.

Embodiment 2

Although a liquid crystal display according to Embodiment 2 hasdifferent layout of an element and wiring in a shift register, theliquid crystal display according to Embodiment 2 is substantiallyidentical to a liquid crystal display of Embodiment 1 except for adifference.

In Embodiment 1, a wiring group 78 is arranged in a region betweentransistors Tr2 to Tr4 (control element region 77) and a display region7. On the other hand, in the present embodiment, as illustrated in FIG.15, the transistors Tr2 to Tr4 (control element region 77) are arrangedin a region between the wiring group 78 and the display region 7.Embodiments 1 and 2 have a common feature in that the wiring group 78and the transistors Tr2 to Tr4 (control element region 77) are arrangedin a region between the display region 7 and an output transistor Tr1.

An array substrate 10 includes a strip region (hereinafter referred toas a seal-coating region) 63 sandwiched between thick dashed lines, anda seal 62 is formed in a strip on the seal-coating region 63 not toprotrude from the seal-coating region 63. One end of the seal-coatingregion 63 is set in a region between a bootstrap capacitor CB1 and anend 10 a of the array substrate 10, whereas the other end is set in aregion between the transistors Tr2 to Tr4 (control element region 77)and the display region 7. The seal-coating region 63 includes a region64 in which the output transistor Tr1 and the bootstrap capacitor CB1are arranged, and a region 66 in which the transistors Tr2 to Tr4(control element region 77) and wiring 74 to 76 (wiring group 78) arearranged. The region 66 corresponds to the above-described first region,and the region 64 corresponds to the above-described second region. Inthis way, in the present embodiment, different from ComparativeEmbodiment 1, the output transistor Tr1 and the bootstrap capacitor CB1are arranged in the seal-coating region 63.

The seal 62 is arranged to cover at least part or all of the outputtransistor Tr1 and part or all of the wiring group 78. As long as theseal 62 does not protrude from the seal-coating region 63, it is notparticularly limited whether the seal 62 covers regions other than theseregions. For example, the seal 62 may be arranged to cover all of theoutput transistor Tr1, all of the wiring group 78, and a partial regionor entire region of the control element region 77. The seal 62 may bearranged to cover part or all of the bootstrap capacitor CB1, all of theoutput transistor Tr1, all of the wiring group 78, and a partial regionor entire region of the control element region 77. In this way, the seal62 includes a first portion that is adjacent to a liquid crystal layer61 and a second portion that is adjacent to the first portion. The firstportion is arranged on the region 66, and the second portion is arrangedon the region 64.

In the present embodiment, in the same manner as in Embodiment 1, theoutput transistor Tr1 and the bootstrap capacitor CB1 are arranged in aregion between the end 10 a of the array substrate 10 and the controlelement region 77. Therefore, also in the present embodiment, it ispossible to reduce occurrence of quality problems and to improveadhesive strength between substrates.

In each of Embodiments 1 and 2, arrangement places of the outputtransistor Tr1 and the bootstrap capacitor CB1 may be transposed.

Embodiment 3

A liquid crystal display according to Embodiment 3 is substantiallyidentical to a liquid crystal display of Embodiment 1 except for alayout of an element and wiring in a shift register being different.

In the present embodiment, as illustrated in FIG. 16, transistors Tr2 toTr4 (control element region 77) are arranged in a region between an end10 a of an array substrate 10 and a bootstrap capacitor CB1.

The array substrate 10 includes a strip region (hereinafter referred toas a seal-coating region) 63 sandwiched between thick dashed lines, anda seal 62 is formed in a strip on the seal-coating region 63 not toprotrude from the seal-coating region 63. One end of the seal-coatingregion 63 is set in a region between the control element region 77 andthe end 10 a of the array substrate 10, whereas the other end is set ina region between wiring 74 and a display region 7. The seal-coatingregion 63 includes a region 64 in which an output transistor Tr1 and thebootstrap capacitor CB1 are arranged, a region 67 in which thetransistors Tr2 to Tr4 are arranged, and a region 68 in which wiring 74to 76 (wiring group 78) are arranged. The region 68 corresponds to theabove-described first region, and the region 64 corresponds to theabove-described second region. In this way, in the present embodiment,different from Comparative Embodiment 1, the output transistor Tr1 andthe bootstrap capacitor CB1 are arranged in the seal-coating region 63.

The seal 62 is arranged to cover at least part or all of the outputtransistor Tr1 and part or all of the wiring 76. As long as the seal 62does not protrude from the seal-coating region 63, it is notparticularly limited whether the seal 62 covers regions other than theseregions. For example, the seal 62 may be arranged to cover part or allof the bootstrap capacitor CB1, all of the output transistor Tr1, andall of the wiring 76. The seal 62 may be arranged to cover a partialregion or entire region of the control element region 77, all of thebootstrap capacitor CB1, all of the output transistor Tr1, all of thewiring 76, and part or all of wiring 75. The seal 62 may be arranged tocover a partial region or entire region of the control element region77, all of the bootstrap capacitor CB1, all of the output transistorTr1, all of the wiring 76, all of the wiring 75, and part or all of thewiring 74. In this way, the seal 62 includes a first portion that isadjacent to a liquid crystal layer 61 and a second portion that isadjacent to the first portion. The first portion is arranged on theregion 68, and the second portion is arranged on the region 64.

In the present embodiment, the output transistor Tr1 and the bootstrapcapacitor CB1 are arranged in a region between the end 10 a of the arraysubstrate 10 and the wiring 76. Accordingly, the wiring group 78 can bearranged on a display region 7 side of the output transistor Tr1 and thebootstrap capacitor CB1. In addition, it is possible to performprovisional hardening and main hardening of a sealing material on theregion 68 in which the wiring 74 to 76 are arranged. On the other hand,it is possible to perform main hardening of the sealing material on theregion 64 in which the output transistor Tr1 and the bootstrap capacitorCB1 are arranged. Consequently, it is possible to control the sealingmaterial component from dissolving in the liquid crystal layer by thetime of completion of the main seal hardening process. In addition, itis possible to define the seal-coating region 63 to be wider.Furthermore, it is possible to control occurrence of liquid crystalleakage. Therefore, in the same manner as in Embodiment 1, it ispossible to reduce occurrence of quality problems and to improveadhesive strength between substrates.

However, the present embodiment differs from Embodiment 1 in that thesealing material portion that undergoes provisional hardening and mainhardening is separately arranged.

Embodiment 4

A liquid crystal display according to Embodiment 4 is substantiallyidentical to a liquid crystal display of Embodiment 3 except for alayout of an element and wiring in a shift register being different.

In Embodiment 3, transistors Tr2 to Tr4 (control element region 77) arearranged in a region between an end 10 a of an array substrate 10 and abootstrap capacitor CB1. On the other hand, in the present embodiment,as illustrated in FIG. 17, a wiring group 78 is arranged in a regionbetween the end 10 a of the array substrate 10 and an output transistorTr1. Embodiments 3 and 4 have a common feature in that the outputtransistor Tr1 and the bootstrap capacitor CB1 are arranged in a regionbetween the wiring group 78 and the transistors Tr2 to Tr4 (controlelement region 77).

The array substrate 10 includes a strip region (hereinafter referred toas a seal-coating region) 63 sandwiched between thick dashed lines, anda seal 62 is formed in a strip on the seal-coating region 63 not toprotrude from the seal-coating region 63. One end of the seal-coatingregion 63 is set between wiring 74 and the end 10 a, whereas the otherend is set in a region between the transistors Tr2 to Tr4 (controlelement region 77) and a display region 7. The seal-coating region 63includes a region 64 in which the output transistor Tr1 and thebootstrap capacitor CB1 are arranged, a region 67 in which thetransistors Tr2 to Tr4 are arranged, and a region 68 in which wiring 74to 76 (wiring group 78) are arranged. The region 67 corresponds to theabove-described first region, and the region 64 corresponds to theabove-described second region. In this way, in the present embodiment,different from Comparative Embodiment 1, the output transistor Tr1 andthe bootstrap capacitor CB1 are arranged in the seal-coating region 63.

The seal 62 is arranged to cover at least part or all of the bootstrapcapacitor CB1, and a partial region or entire region of the controlelement region 77. As long as the seal 62 does not protrude from theseal-coating region 63, it is not particularly limited whether the seal62 covers regions other than these regions. For example, the seal 62 maybe arranged to cover part or all of the output transistor Tr1, all ofthe bootstrap capacitor CB1, and a partial region or entire region ofthe control element region 77. The seal 62 may be arranged to cover partor all of the wiring 76, all of the output transistor Tr1, all of thebootstrap capacitor CB1, and a partial region or entire region of thecontrol element region 77. The seal 62 may be arranged to cover part orall of the wiring 75, all of the wiring 76, all of the output transistorTr1, all of the bootstrap capacitor CB1, and a partial region or entireregion of the control element region 77. The seal 62 may be arranged tocover part or all of the wiring 74, all of the wiring 75, all of thewiring 76, all of the output transistor Tr1, all of the bootstrapcapacitor CB1, and a partial region or entire region of the controlelement region 77. In this way, the seal 62 includes a first portionthat is adjacent to a liquid crystal layer 61 and a second portion thatis adjacent to the first portion. The first portion is arranged on theregion 67, and the second portion is arranged on the region 64.

In the present embodiment, in the same manner as in Embodiment 1, theoutput transistor Tr1 and the bootstrap capacitor CB1 are arranged in aregion between the end 10 a of the array substrate 10 and the controlelement region 77. Therefore, also in the present embodiment, it ispossible to reduce occurrence of quality problems and to improveadhesive strength between substrates.

The wiring group 78 is arranged in a region between the end 10 a of thearray substrate 10 and the output transistor Tr1. Accordingly, it ispossible to protect the transistors Tr1 to Tr4 from static electricitythat intrudes from outside by the wiring group 78.

In each of Embodiments 3 and 4, arrangement places of the outputtransistor Tr1 and the bootstrap capacitor CB1 may be transposed.

Embodiment 5

A liquid crystal display according to Embodiment 5 is substantiallyidentical to a liquid crystal display of Embodiment 1 except for alayout of an element and wiring in a shift register being different.

In the present embodiment, as illustrated in FIG. 18, transistors Tr2 toTr4 (control element region 77) are arranged in a region between adisplay region 7 and a bootstrap capacitor CB1, and a wiring group 78 isarranged in a region between an output transistor Tr1 and the bootstrapcapacitor CB1.

An array substrate 10 includes a strip region (hereinafter referred toas a seal-coating region) 63 sandwiched between thick dashed lines, anda seal 62 is formed in a strip on the seal-coating region 63 not toprotrude from the seal-coating region 63. One end of the seal-coatingregion 63 is set in a region between the output transistor Tr1 and anend 10 a of the array substrate 10, whereas the other end is set in aregion between the transistors Tr2 to Tr4 (control element region 77)and the display region 7. The seal-coating region 63 includes a region69 in which the output transistor Tr1 is arranged, a region 70 in whichthe bootstrap capacitor CB1 is arranged, a region 67 in which thetransistors Tr2 to Tr4 are arranged, and a region 79 in which wiring 74to 76 (wiring group 78) are arranged. The regions 67 and 79 correspondto the above-described first region, and the regions 69 and 70correspond to the above-described second region. In this way, in thepresent embodiment, different from Comparative Embodiment 1, the outputtransistor Tr1 and the bootstrap capacitor CB1 are arranged in theseal-coating region 63.

The seal 62 is (1) arranged to cover at least part or all of the outputtransistor Tr1 and part or all of the wiring 74, or (2) arranged tocover at least part or all of the bootstrap capacitor CB1 and a partialregion or entire region of the control element region 77. In addition,the seal 62 includes a first portion that is adjacent to a liquidcrystal layer 61 and a second portion that is adjacent to the firstportion. In each of the cases (1) and (2), as long as the seal 62 doesnot protrude from the seal-coating region 63 and the first portion isnot arranged on the bootstrap capacitor CB1, it is not particularlylimited whether the seal 62 covers regions other than these regions.

In the case of (1), for example, the seal 62 may be arranged to coverall of the output transistor Tr1 and all of the wiring group 78. Theseal 62 may be arranged to cover part or all of the output transistorTr1, all of the wiring group 78, all of the bootstrap capacitor CB1, anda partial region or entire region of the control element region 77.

In the case of (2), for example, the seal 62 may be arranged to coverall of the bootstrap capacitor CB1 and the entire region of the controlelement region 77. The seal 62 may be arranged to cover part or all ofthe wiring group 78, all of the bootstrap capacitor CB1, and a partialregion or entire region of the control element region 77. The seal 62may be arranged to cover part or all of the output transistor Tr1, allof the wiring group 78, all of the bootstrap capacitor CB1, and apartial region or entire region of the control element region 77.

In the present embodiment, the output transistor Tr1 is arranged in aregion between the end 10 a of the array substrate 10 and the wiringgroup 78, and the bootstrap capacitor CB1 is arranged in a regionbetween the end 10 a of the array substrate 10 and the control elementregion 77. Accordingly, the wiring group 78 can be arranged on a displayregion 7 side of the output transistor Tr1, and the control elementregion 77 can be arranged on a display region 7 side of the bootstrapcapacitor CB1. In addition, it is possible to perform provisionalhardening and main hardening of a sealing material on the region 67 inwhich the transistors Tr2 to Tr4 are arranged, and on the region 79 inwhich the wiring group 78 is arranged. On the other hand, it is possibleto perform main hardening of the sealing material on the region 69 inwhich the output transistor Tr1 is arranged, and on the region 70 inwhich the bootstrap capacitor CB1 is arranged. Consequently, it ispossible to control the sealing material component from dissolving inthe liquid crystal layer by the time of completion of the main sealhardening process. In addition, it is possible to define theseal-coating region 63 to be wider. Furthermore, it is possible tocontrol occurrence of liquid crystal leakage. Therefore, in the samemanner as in Embodiment 1, it is possible to reduce occurrence ofquality problems and to improve adhesive strength between substrates.

However, the present embodiment differs from Embodiment 1 in that thesealing material portion that undergoes provisional hardening and mainhardening is separately arranged.

In Embodiment 5, arrangement places of the output transistor Tr1 and thebootstrap capacitor CB1 may be transposed, and arrangement places of thecontrol element region 77 and the wiring group 78 may be transposed.

Various variations of Embodiments 1 to 5 will be described below. Asemiconductor material of each TFT is not particularly limited, but canbe suitably selected. Examples of semiconductor materials include agroup 14 element semiconductor, such as silicon, and an oxidesemiconductor. Furthermore, crystallinity of a semiconductor material ofeach TFT is not particularly limited, but may be a single crystal, apolycrystal, an amorphous, or a microcrystal, and may include two ormore types of these crystal structures. However, when an outputtransistor contains amorphous silicon, from a viewpoint of enlarging itsdriving capability, a channel width of the output transistor and a sizeof a bootstrap capacitor become particularly large. Therefore, theoutput transistor containing amorphous silicon can remarkably perform aneffect of reducing occurrence of quality problems and an effect ofimproving adhesive strength of the seal. The oxide semiconductorpreferably contains oxygen (O), and at least one element selected fromthe group consisting of indium (In), gallium (Ga), zinc (Zn), aluminum(Al), and silicon (Si). More preferably, the oxide semiconductorcontains In, Ga, Zn, and O.

A type of each TFT is not particularly limited to a bottom gate type,but can be suitably selected.

Furthermore, a TFT other than a gate driver TFT may further be arrangedin the picture-frame region.

In addition, the number and arrangement place of the unit circuit thatsatisfies the above-described layout are not particularly limited, butcan be suitably configured. That is, at least one unit circuit mayinclude either one of the above-described layouts, and part or all ofthe unit circuits may include either one of the above-described layouts.However, from a viewpoint of performing the above-described effectparticularly effectively, all the unit circuits preferably includeeither one of the above-described layouts.

Furthermore, a type of an element and wiring of each gate driver is notparticularly limited, but can be suitably determined, except for anoutput transistor and a bootstrap capacitor.

Embodiments 1 to 5 may be combined with each other. For example, unitcircuits of different layouts may be formed in a common shift register,and a plurality of shift registers may include unit circuits of layoutsdifferent from each other.

REFERENCE SIGNS LIST

-   1 liquid crystal panel-   2 display section-   3 pixel-   4 pixel TFT-   drive circuit for source bus lines (source driver)-   6 a, 6 b drive circuit for gate bus lines (gate driver)-   7 display region-   8 picture-frame region-   9 pixel electrode-   array substrate-   10 a end-   11 insulating substrate-   12, S1 to Sm source bus lines-   13, G1 to Gn gate bus lines-   14 common transfer electrode-   16 common trunk wiring-   17 common bus line-   18,19 lead-out wiring-   input wiring-   26, 27, 28, 29, 30 terminal-   31 first electrode-   32 second electrode-   41 gate electrode-   42 gate insulator-   43 i layer (semiconductor active layer)-   44 n+ layer-   source electrode-   46 drain electrode-   47,48 insulating layer-   50 opposed substrate-   51 insulating substrate-   52 black matrix (BM)-   61 liquid crystal layer-   62 seal-   63 seal-coating region-   64 to 69, 70, 79 region-   71 pixel array-   72 display control circuit-   73 a, 73 b shift register-   74 to 76 wiring-   77 control element region-   78 wiring group-   Pij pixel circuit-   SR1 to SRn unit circuit-   INa, INb input terminal-   CKA, CKB clock terminal-   VSS power terminal-   OUT output terminal-   Tr1 to Tr4 transistor-   CB1 bootstrap capacitor

The invention claimed is:
 1. An active matrix substrate comprising: aninsulating substrate, a shift register monolithically formed on theinsulating substrate, a plurality of gate bus lines, a first end of theinsulating substrate, and a display region, the shift register includesa plurality of unit circuits that are multistage-connected and wiringconnected to the plurality of unit circuits, the shift register beingarranged in a region between the first end and the display region, atleast one of the plurality of unit circuits includes: a clock terminalinto which a clock signal is input, an output terminal connected to acorresponding gate bus line, the output terminal outputting an outputsignal, a first transistor with one of a source and a drain beingconnected to the clock terminal and the other of the source and thedrain being connected to the output terminal, a second transistorelectrically connected to a gate of the first transistor; and acapacitor with a first terminal being directly connected to a gate ofsaid first transistor and a second terminal being directly connected tothe output terminal, and the wiring connected to the plurality of unitcircuits includes at least one of a first wiring for supplying alow-level potential to the unit circuit and a second wiring fortransmitting the clock signal to the unit circuit, the capacitor isarranged at a position different from a position of the first transistorand adjacent to the first transistor in a plan view, the firsttransistor and the capacitor are arranged in a region between the firstend and the second transistor, the wiring connected to the plurality ofunit circuits is arranged in a region between one of the firsttransistor and the capacitor and the first end, the second transistor isarranged in a region between one of the first transistor and thecapacitor and the display region.
 2. The active matrix substrateaccording to claim 1, wherein the first transistor, the secondtransistor, and the capacitor are arranged along a direction where theplurality of gate bus lines extend.
 3. The active matrix substrateaccording to claim 1, wherein at least one of the plurality of unitcircuits includes a plurality of the second transistor.
 4. The activematrix substrate according to claim 1, wherein at least a portion of thecapacitor is arranged in a region between the first transistor and thesecond transistor.
 5. The active matrix substrate according to claim 4,wherein the wiring is arranged in a region between the first transistorand the first end, and the second transistor is arranged in a regionbetween the capacitor and the display region.
 6. The active matrixsubstrate according to claim 1, wherein at least a portion of thecapacitor is arranged in a region between the first transistor and thewiring connected to the plurality of unit circuits.
 7. The active matrixsubstrate according to claim 6, wherein the wiring is arranged in aregion between the capacitor and the first end, and the secondtransistor is arranged in a region between the first transistor and thedisplay region.
 8. A liquid crystal display comprising: the activematrix substrate according to claim 1, a second substrate facing theactive matrix substrate, and a seal provided between the active matrixsubstrate and the second substrate.
 9. The liquid crystal displayaccording to claim 8, wherein the second substrate includes a lightshielding portion that faces the shift register.